PRTG Manual: NetFlow V5 Sensor

The NetFlow V5 sensor receives traffic data from a NetFlow V5 compatible device and shows the traffic by type. Ensure the sensor matches the NetFlow version your device is exporting! There are several filter options available to divide traffic into different channels.

This sensor can show the following traffic types in kbit per second:

Chat (IRC, AIM)

Citrix

FTP/P2P (file transfer)

Infrastructure (network services: DHCP, DNS, Ident, ICMP, SNMP)

Mail (mail traffic: IMAP, POP3, SMTP)

NetBIOS

Remote control (RDP, SSH, Telnet, VNC)

WWW (web traffic: HTTP, HTTPS)

Total traffic

Other protocols (other UDP and TCP traffic)

Which channels the sensor actually shows might depend on the monitored device and the sensor setup.

NetFlow V5 Sensor

Remarks

You must enable NetFlow export of the respective version on the monitored device for this sensor to work. The device must send the flow data stream to the IP address of the PRTG probe system on which the sensor is set up (either a local or remote probe).

This sensor type cannot be used in cluster mode. You can set it up on a local probe or remote probe only, not on a cluster probe.

This sensor type can have a high impact on the performance of your monitoring system. Please use it with care! We recommend that you use no more than 50 sensors of this sensor type on each probe.

You cannot add this sensor type to the Hosted Probe of a PRTG hosted by Paessler instance. If you want to use this sensor type, please add it to a remote probe device.

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the setting fields that are required for creating the sensor. Therefore, you will not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.

Sensor Settings

On the details page of a sensor, click the Settings tab to change its settings.

Usually, a sensor connects to the IP Address or DNS Name of the parent device where you created this sensor. See the Device Settings for details. For some sensor types, you can define the monitoring target explicitly in the sensor settings. See below for details on available settings.

Enter one or more Tags, separated by spaces or commas. You can use tags to group sensors and use tag–filtered views later on. Tags are not case sensitive. We recommend that you use the default value.

There are default tags that are automatically predefined in a sensor's settings when you add a sensor. See section Default Tags below.

You can add additional tags to the sensor if you like. Other tags are automatically inherited from objects further up in the device tree. These are visible above as Parent Tags.

It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with round parentheses (()) or angle brackets (<>).

Priority

Select a priority for the sensor. This setting determines where the sensor is placed in sensor lists. Top priority is at the top of a list. Choose from one star (low priority) to five stars (top priority).

Default Tags

bandwidthsensor, netflowsensor

NetFlow Specific Settings

Receive NetFlow Packets on UDP Port

Enter the UDP port number on which the flow packets are received. It must match the one you have configured in the NetFlow export options of your hardware router device. Please enter an integer value.

When configuring export, make sure you select the appropriate NetFlow version for this sensor.

Sender IP

Enter the IP address of the sending device you want to receive the NetFlow from. Enter an IP address to receive data from a specific device only, or leave the field empty to receive data from any device on the specified port.

Receive NetFlow Packets on IP

Select the IP address(es) on which PRTG listens to NetFlow packets. The list of IP addresses you see here is specific to your setup. To select an IP address, add a check mark in front of the respective line. You can also select and deselect all items by using the check box in the table head. The IP address selected here must match the one you have configured in the NetFlow export options of your hardware router device.

When configuring export, make sure you select the appropriate NetFlow version for this sensor.

Active Flow Timeout (Minutes)

Enter a time span in minutes after which new flow data must be received. If the timeout is reached and no new data was received during this time, the sensor switches to an Unknownstatus. Please enter an integer value.

We recommend that you set the timeout one minute longer than the respective timeout configured in your hardware router device. The maximum timeout is 60 minutes.

If the target device sends incorrect time information that results in wrong monitoring data, please try to use 0 as active flow timeout. This will ignore the start and stop information of a flow as provided by the device and account all data to the current point in time. It might result in spikes but all data will be captured.

Sampling Mode

Define if you want to use the sampling mode. This setting must match the setting in the flow exporter. Choose between:

Off: The standard flow will be used.

On: Switch into sampling mode and specify the sampling rate below.

Sampling Rate

This field is only visible when sampling mode is On above. Enter a number that matches the sampling rate in your exporter device. If the number is different, monitoring results will be incorrect. Please enter an integer value.

Log Stream Data to Disk (for Debugging)

Define if you want the probe to write a logfile of the stream and packet data to the data folder (see Data Storage). Choose from:

None (recommended): Do not write additional logfiles. Recommended for normal use cases.

Only for the 'Other' channel: Only write logfiles of data that is not filtered otherwise and therefore accounted to the default Other channel.

All stream data: Write logfiles for all data received.

Use with caution! When enabled, huge data files can be created. Please use for a short time and for debugging purposes only.

Channel Configuration

Channel Selection

Define the categories the sensor accounts the traffic to. There are different groups of traffic available. Choose from:

Web: Internet web traffic.

File Transfer: Traffic from FTP.

Mail: Internet mail traffic.

Chat: Traffic from chat and instant messaging.

Remote Control: Traffic from remote control applications, such as RDP, SSH, Telnet, and VNC.

Infrastructure: Traffic from network services, such as DHCP, DNS, Ident, ICMP, and SNMP.

NetBIOS: Traffic from NetBIOS communication.

Citrix: Traffic from Citrix applications.

Other Protocols: Traffic from various other protocols via UDP and TCP.

For each traffic group, you can select how many channels will be used for each group, that is, how detailed the sensor divides the traffic. For each group, choose from:

No (X icon): Do not account traffic of this group in its own channel. All traffic of this group is accounted to the default channel named Other.

Yes (check mark icon): Count all traffic of this group and summarize it into one channel.

Detail (magnifier icon): Count all traffic of this group and further divide it into different channels. The traffic appears in several channels as shown in the Content column. Extensive use of this option can cause load problems on your probe system. We recommend that you set specific, well-chosen filters for the data you really want to analyze.

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel will always be displayed below the sensor's name. The available options depend on what channels are available for this sensor.

You can set another primary channel later by clicking the pin symbol of a channel in the sensor's Overview tab.

Graph Type

Define how different channels will be shown for this sensor.

Show channels independently (default): Show an own graph for each channel.

Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This will generate an easy-to-read graph that visualizes the different components of your total traffic. This option cannot be used in combination with manual Vertical Axis Scaling (available in the Sensor Channel Settings settings).

Stack Unit

This setting is only available if stacked graphs are selected above. Choose a unit from the list. All channels with this unit will be stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Primary Toplist

Primary Toplist

Define which will be your primary Toplist. It will be shown in maps when adding a toplist object. Choose from:

Top Talkers

Top Connections

Top Protocols

[Any custom Toplists you have added]

Inherited Settings

By default, all following settings are inherited from objects higher in the hierarchy and should be changed there, if necessary. Often, best practice is to change them centrally in the Root group's settings, see section Inheritance of Settings for more information. To change a setting only for this object, disable inheritance by clicking the button next to inherit from under the corresponding setting name. You will then see the options described below.

Select a scanning interval (seconds, minutes, or hours) from the list. The scanning interval determines the time the sensor waits between two scans. You can change the available intervals in the system administration on PRTG on premises installations.

If a Sensor Query Fails

Define the number of scanning intervals that a sensor has time to reach and check a device again in case a sensor query fails. The sensor can try to re-reach and check a device several times, depending on the option you select here, before it will be set to a Downstatus. This helps you avoid false alarms if the monitored device has only temporary issues. For previous scanning intervals with failed requests, the sensor will show a Warning status. Choose from:

Set sensor to down immediately: The sensor will show an error immediately after the first failed request.

Set sensor to warning for 1 interval, then set to down (recommended): After the first failed request, the sensor will show a warning status. If the following request also fails, the sensor will show an error.

Set sensor to warning for 2 intervals, then set to down: Show an error status only after three consecutively failed requests.

Set sensor to warning for 3 intervals, then set to down: Show an error status only after four consecutively failed requests.

Set sensor to warning for 4 intervals, then set to down: Show an error status only after five consecutively failed requests.

Set sensor to warning for 5 intervals, then set to down: Show an error status only after six consecutively failed requests.

Sensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval until they show an error. It is not possible to set a WMI sensor to Down immediately, so the first option will not apply to these sensor types. All other options can apply.

If a sensor has defined error limits for channels, it will always show a Down status immediately, so no "wait" option will apply.

If a channel uses lookup values, it will always show a Down status immediately, so no "wait" options will apply.

Schedules, Dependencies, and Maintenance Window

Inheritance for schedules, dependencies, and maintenance windows cannot be interrupted. The corresponding settings from the parent objects will always be active. However, you can define additional settings here. They will be active at the same time as the parent objects' settings.

Schedule

Select a schedule from the list. Schedules can be used to monitor for a certain time span (days, hours) every week. With the period list option it is also possible to pause monitoring for a specific time span. You can create new schedules and edit existing ones in the account settings.

Schedules are generally inherited. New schedules will be added to existing ones, so all schedules are active at the same time.

Maintenance Window

Specify if you want to set up a one-time maintenance window. During a maintenance window, the current sensor and all child objects will not be monitored. They will be in a Paused status instead. Choose between:

Not set (monitor continuously): No maintenance window will be set and monitoring will always be active.

Set up a one-time maintenance window: Pause monitoring within a maintenance window. You can define a time span for a monitoring pause below and change it even for a currently running maintenance window.

To terminate a current maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.

Maintenance Begins

This field is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the maintenance window.

Maintenance Ends

This field is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the maintenance window.

Dependency Type

Define a dependency type. You can use dependencies to pause monitoring for an object depending on the status of another object. You can choose from:

Use parent: Use the dependency type of the parent device.

Select a sensor: Use the dependency type of the parent device. Additionally, pause the current sensor if another specific sensor is in a Down status or in a Paused status caused by another dependency. Select below.

Master sensor for parent: Make this sensor the master object for its parent device. The sensor will influence the behavior of its parent device: If the sensor is in a Down status, the device will be paused. For example, it is a good idea to make a Ping sensor the master object for its parent device to pause monitoring for all other sensors on the device in case the device cannot even be pinged. Additionally, the sensor will be paused if the parent group is paused by another dependency.

Testing your dependencies is easy! Simply select Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later, all dependent objects should be paused. You can check all dependencies in your PRTG installation by selecting Devices | Dependencies from the main menu bar.

Dependency

This field is only visible if you enable Select a sensor above. Click the Search button and use the object selector to select a sensor on which the current sensor will depend.

Dependency Delay (Sec.)

This field is only visible if you enable Select a sensor above. Define a time span in seconds for dependency delay.

After the master sensor for this dependency comes back to an Up status, monitoring of the dependent objects will be additionally delayed by the defined time span. This can help avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Please enter an integer value.

This setting is not available if you set this sensor to Use parent or to be the Master sensor for parent. In this case, please define delays in the parent Device Settings or in its parent Group Settings.

Define which user group(s) will have access to the object you're editing. A table with user groups and types of access rights is shown. It contains all user groups from your setup. For each user group, you can choose from the following access rights:

Inherited: Use the access rights settings of the parent object.

None: Users in this group cannot see or edit the object. The object neither shows up in lists nor in the device tree. Exception: If a child object is visible to the user, the object is visible in the device tree, though not accessible.

Read: Users in this group can see the object and review its monitoring results.

Write: Users in this group can see the object, review its monitoring results, and edit the object's settings. They cannot edit access rights settings.

Full: Users in this group can see the object, review its monitoring results, edit the object's settings, and edit access rights settings.

You can create new user groups in the System Administration—User Groupssettings. To automatically set all objects further down in the hierarchy to inherit this object's access rights, set a check mark for the Revert children's access rights to inherited option.

For each type of sensor channel, define the unit in which data is displayed. If defined on probe, group, or device level, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available):

Bandwidth

Memory

Disk

File

Custom

Custom channel types can be set on sensor level only.

Toplists

For all xFlow and Packet Sniffer sensors, there are Toplists available on the sensor's Overview tab. Using Toplists, you can review traffic data of small time periods in great detail.

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